Marouane Fellaini was sent off for brainlessly headbutting Sergio Aguero in an otherwise forgettable 0-0 draw between Champions League qualification rivals Manchester United and Manchester City on Thursday.

Booked for tripping Aguero in the 84th minute, Fellaini fouled him again seconds later and then blatantly butted the Argentinian, leaving referee Martin Atkinson no option but to send the Belgian off.

City remain fourth, a point behind third-place Liverpool with a game in hand, with United -- who also have a game in hand on Jurgen Klopp's side -- a point further back in fifth place.

"We were the better team in the first half, they were the better team in the second half," said United manager Jose Mourinho.

"They had more of the ball, more chances, but my players were amazing the way they fought.

"Marouane Fellaini is frustrated. He says that with another player, it would probably not be a red card."

While United are now unbeaten in 24 Premier League games, equalling the club record, the Etihad Stadium stalemate means City retain the upper hand in the push for a top-four finish.

But despite controlling the game, City came no closer to scoring than an early Aguero effort that hit the post, while substitute Gabriel Jesus had an injury-time header disallowed for offside.

City also lost goalkeeper Claudio Bravo to an apparent calf injury, sustained as he caught a high ball, with Willy Caballero taking his place for the last 14 minutes after Bravo was stretchered off.

"They created two clear chances and I am satisfied," City manager Pep Guardiola told BBC Sport.

"We all have tough games coming up now and we know it's not an option to not win these games."

City remain on course for a top-four finish, their last remaining objective after last weekend's FA Cup semi-final loss to Arsenal consigned Guardiola to his first trophy-less season as a coach.

United could yet qualify for the Champions League by winning the Europa League.

But in the main, Thursday's drab derby served to illustrate why the Manchester rivals are squabbling over fourth place rather than fighting for the title.